1. Field of the Invention
This invention relates to a multicoin (multitoken) discriminator comprising a chute having a vertically inclined track on which infed coins (tokens) roll. The coin discriminator is intended for an automatic object or service vending machine.
2. Description of the Prior Art
Multicoin discriminators as described in French patent applications 2,461,987 and 2,466,055 comprise coin dimension recognizing means in the form of two electromagnetic field producing coils on either side of the coin roll-in chute. The diameters of the coils are such that the upper tip of a coin having a minimum acceptable diameter enters only a small portion of the coil electromagnetic field; a coin having the maximum acceptable diameter enters the entire electromagnetic field. One of the coils, referred to as an oscillating coil, is connected to an oscillating circuit which delivers a high frequency signal, typically 100 kHz. The other coil, a so-called receiving coil, transmits a voltage to voltage comparison means; the voltage is proportional to the magnetic flux intensity through which the upper part of each coin passes. Reference voltages representative of the diameters of varying acceptable coin types are compared with the voltage transmitted by the receiving coil to deduce whether the coin should be accepted; if the coin is acceptable it has a diameter between the minimum and maximum diameters; otherwise the coin is refused.
In the foregoing patent applications, the coin alloy detecting means make use of the same voltage comparison principle.
Another coin discriminator, disclosed in French patent application 2,448,752, selects only one type of coin, i.e., admits only coins having a predetermined diameter and made of a predetermined alloy or material.
The principle behind the means for recognizing alloys resides in the description hereinabove. The alloy recognizing means also comprises two coils disposed opposite each other. One of the coils is excited by an a.c. generator. A signal induced in the other coil has an amplitude that is compared with a predetermined voltage to determine if the coin between the coils is acceptable; if the amplitude is less than the predetermined voltage the coin is acceptable.
The coin dimension recognizing means taught in French patent application 2,448,752 comprises two light sources and phototransistor light detecting pairs. The light detectors are spaced from each other by a distance virtually equal to the acceptable coin type diameter. Should one or both the phototransistors be excited, the infed coin does not have the required diameter and is rejected.
Known previous discriminators thus adopt coin diameter and alloy as the sole selection criteria. An infed coin having the acceptable diameter and alloy is therefore accepted regardless of thickness. This offers a further non-negligible opportunity of fraudulently introducing improper coins or slugs into the vending machine. Moreover, the diameter recognizing means taught in French patent application 2,466,055 permits acceptance of coins having diameters that vary over only a relatively small range. If the vending machine is to accept coins having many different diameters, the measurement device for distinguishing between the diameters require high sensitivity and very precise setting; the number of voltage comparing circuits equals the number of different diameters. The alloy recognizing means also requires a number of voltage comparing circuits equal to the number of denominations to be detected.